Isn't it sort of funny that they think the asteroid might be some new material, or at least something tougher than iron, yet they are planning to use a magnet to pull up pieces? What happens if it's non-ferrous...
"There's a chance its not iron but something new!"
"What chance is that?"
"Its inverse to the chance we told our funders, who gave us millions to collect it with a magnet, that it was iron."
"So its pretty guaranteed its iron"
"Yup".
"Aren't your funders concerned you are saying it could be something different than iron?"
"You see the name of the university and a few corporations on the ship? Would you be talking to us if we were just getting a run of the mill iron metorite?"
If it's an extra hard iron alloy it would be more interesting because they can analyze it and perhaps reproduce the composition and perhaps the heat process that created the meteorite.
If they want mass extraction after that, then potentially a form a dredging could be used (vacuum and filter could work to leave the sand and silt on the bottom).